The overall objective of this research project is to identify factors which account for some portion of the variance of blood pressure among children, adolescents, and young adults. Follow-up examinations are planned among a cohort of females formed in 1965-1967, and of their children: (1) to determine whether previously measured urinary electrolyte excretion rates, dietary, anthropometric, and socioeconomic variables (1968-1970) are correlated with current blood pressure levels; (2) to determine whether disparities in blood pressure and in the urinary excretion rates of Na and K observed between black and white adolescent females examined in 1969 or 1970 are still present; (3) to determine whether the abnormally low Na/K net flux ratio in erythrocytes of persons with hypertension recently described: a) can be docmented in our laboratory, b) exists in a black population, c) does account for any of the blood pressure disparities between: 1) black and white females, 2) females (and children born to them) who are diagnosed as having preeclampsia during their first pregnancy as compared to females (and children born to them) not so diagnosed during their first pregnacy (1966-1970), and d) whether this factor (Na/K flux ratio in RBC) interacts with other factors postulated to influence blood pressure levels, and 4) to compare blood pressure levels and urinary electrolyte excretion rates of a sample of adolescents in high school now with similar data obtained on a cohort of similar composition during 1965-1970. To explore the first three objectives data will be obtained by follow-up examination of cohorts of participants of earlier studies (1965-1971), while that to be acquired under the last objective will be obtained by examination of a sample of students now in high school.